Multiple enhancements to support more flexibility in configuration

This change set address a few issues, which were implemented by us specifically to support the ability to have indexes that support multi-tenant databases.  Specifically, we did the following:
- When using "only" in the mapping, transient properties will now be allowed
- "indexId" may now be added to mapping which will allow a change to which field is used as _id in the index.
- Additionally, "indexId" will support multiple fields
- Corrected a problem where counting the instances of a domain class sometimes occurred using the wrong hibernate session